1. Field of the Invention
The present invention relates to a dual mode mobile terminal, and more particularly, to a dual mode mobile terminal in an MIMO wireless communication system and controlling method thereof.
2. Discussion of the Related Art
Recently, the wireless communication fields consistently keep being evolved in aspect of fast data transmission and reception as well as voice call. And, ongoing attentions are paid to the 4th generation mobile communication technology, e.g., LTE (long term evolution) wireless communication system. Yet, in a current situation that the 4th generation communication network and the commercialized 3rd generation communication network coexist, a mobile communication terminal or a mobile communication data card should include the 3G mobile communication technology, which is already commercialized and being used globally, as well as the 4th generation mobile communication technology. Therefore, in order to support both of the next generation mobile communication technology and the previous generation mobile communication technology, a mobile terminal (hereinafter called a dual mode terminal) equipped with a dual modem processor or a data card type device (hereinafter called a dual mode terminal) equipped with a dual modem processor is required.
The dual mode terminal is equipped with two kinds of modems differing from each other in communication scheme and supports the wireless communications using the two kinds of the modems, respectively. And, the dual mode terminal is frequently used in an area in which heterogeneous communication networks coexist. For example of a representative dual mode terminal, attention is paid to a device capable of both LTE (long term evolution) wireless communication and CDMA (code divisional multiple access) wireless communication. Although the description of the present invention is made on the assumption of a multi-mode device capable of communicating with both LTE network and CDMA network, it is apparent to those skilled in the art that the present invention is applicable to wireless communications of other systems.
Meanwhile, MIMO scheme of transmitting and receiving signals using a plurality of transmitting antennas and a plurality of receiving antennas is applied to the wireless communication of the LTE system. According to the MIMO scheme, a transmitting or receiving stage of a wireless communication system uses a plurality of antennas. Therefore, capacity is increased and performance can be enhanced. Moreover, the wireless communication of the CDMA system needs multiple antennas for a diversity scheme from RV-DO REV. A. In the following description, MIMO can be named ‘multi-antenna’.
In the MIMO technology, a reception of one whole message does not depend on a single antenna path. Instead, the MIMO technology completes data in a manner of gathering and integrating data fragments received via multiple antennas. If the MIMO technology is used, a data transmission speed can be enhanced within a cell area of a specific size or a system coverage can be increased by securing a specific data transmission speed. And, this technology is widely applicable to a mobile communication terminal, a relay node and the like. According to the MIMO technology, it is able to overcome the limitation put of a transmission size in a mobile communication according to the related art which adopts a single antenna.